In a semiconductor manufacturing process, a variety of tools are utilized, such as steppers, etchers and the like, each of which requires a constant supply of process gases in order to produce semiconductor devices of uniform quality. A tool may require multiple supply lines of both inert and volatile process gases, such as nitrogen, oxygen, hydrogen, xylene, boron trichloride, silicon trifluoride, argon, etc. Many process gases are flammable, toxic and/or pyrophoric and therefore require special precautions in order to be utilized safely.
A conventional gas handling device is shown in FIG. 1 and indicated generally at 10. Device 10 includes a plurality of gas handling units, including a pair of stop valves 12, a mass flow controller 14 and a filter 16. The units each have inlet and exit ports that are sequentially coupled together by fittings 20. A gas supply (not shown) delivers a flow of process gas to the device's inlet 22, and the device's outlet 24 is coupled to the tool via another length of tubing. To stabilize and support the devices, valves 12 and controller 14 include a mounting block 26, which includes a pair of legs 28 with outwardly extending lower portions 30 that are rigidly secured on a base plate 32, such as an elongate sheet of stainless steel. To secure each mounting block 26 to plate 32, holes are drilled in precise locations on the plate and bolts 34, or other suitable fasteners, are passed through the holes and outwardly extending portions 30 of the blocks to secure the gas handling units in a fixed position on the plate, thereby supporting the gas handling device thereon.
The above-described gas handling device has numerous disadvantages, including, but not limited to, the following:
A primary disadvantage of the gas handling device shown in FIG. 1 is its lack of adjustability. Because units such as valves and pressure transducers are mounted in a fixed position on base plate 32 through holes that are drilled or punched through the base when the units are initially installed thereon, additional units can not be easily added to the device. Specifically, to install an additional gas handling unit to the device shown in FIG. 1, the individual gas handling units must be removed from plate 32 and further spaced apart from each other. Because the addition of the new unit will increase the length of device 10 and change the position of the individual mounting surfaces of the previously mounted gas handling units, new holes must be punched or drilled into plate 32 for the new unit, as well as any displaced old units. This process is not only very time and labor intensive, but also significantly increases the possibility that particulate and other contaminants will be introduced to the gas handling device, as well as to the tool with which the device is used.
It should be understood that the tools, namely the semiconductor processing machines or devices, used in the semiconductor manufacturing process are conventionally housed in a clean room in order to prevent dust, small particulate and other contaminants from being introduced to the gas handling units, the tools and any products made therefrom. Therefore, when multiple holes must be drilled in the stainless steel base plate, there is a significant chance that small shavings, dirt and other contaminants will be created and potentially introduced to the gas handling device or tool. This is true even if the drill used to make the new mounting holes has some form of vacuum or contaminant-trapping mechanism.
Similar to the above discussed problem, the gas handling device shown in FIG. 1 presents other problems relating to adjustability that are encountered when an existing gas handling unit must be replaced. The simplest form of replacement is to remove an existing unit, such as flow controller 14, and replace it with an identical unit. The danger in this replacement is that the sealing surfaces of the unit's inlet and outlet ports may become scratched or damaged because of insufficient clearance between the sealing surface of the flow controller's inlet and outlet ports and the sealing end of fitting 20, which connects the flow controller to adjacent units. In order to prevent the sealing surface of controller 14 from being scratched or damaged, other gas handling units, such as valve 12 or filter 16 must be loosened to provide clearances between the inlet and outlet port of the controller and the respective fittings 20. Therefore, instead of being able to quickly remove and replace an existing unit with an identical replacement unit, the process requires manipulation of multiple units and therefore takes a considerable amount of time and effort.
Even more time and labor intensive problems are caused when an existing unit must be replaced with a unit of a different size. This situation often results in the semiconductor manufacturing process when an existing unit is discontinued by its manufacturer or when a user desires to upgrade or change a particular unit. When this occurs, the existing unit must be removed, and the new unit replaced therefor. Because gas handling units tend to vary in size, shape, and height, this process generally requires the gas handling units on either side of the new unit to be removed and remounted on base plate 32. As discussed above, this involves removing existing units, drilling new holes and remounting the removed units.
An additional problem with existing gas handling devices is that they cannot be quickly removed from the tool with which they are used. Specifically, a particular tool in the semiconductor manufacturing process may use as few as one and as many as eighteen or more gas handling devices to deliver process gas to the tool. If any of the individual gas handling units on any of these gas handling devices fails, the tool must be shut down until the problem is identified and repaired. It should be understood that in addition to the labor, time and materials cost to identify and repair the faulty unit, the user faces even greater losses from the lack of use of the tool during this repair and maintenance period, which can commonly take from several hours to several days.
Once the tool is "brought down" or stopped, the faulty gas handling device must be identified, and the individual gas handling units on the device must be removed, tested, replaced if faulty, and remounted on the device. Furthermore, if the faulty unit is not currently on hand or readily available, the down time problem is extended until another unit may be obtained, or alternatively, the above-discussed problem encountered when new units are used to replace older or less available units is revisited.
An additional problem with conventional gas handling devices is the difficulty a user encounters when gas handling units must be mounted and removed from the device after the device is installed in an operative position to provide process gas to a tool. Specifically, this problem arises because the individual gas handling units are mounted on base plate 32 using a bolt 34 which extends through the unit and the plate and is secured by a nut or other suitable fastener on the underside of plate 32. Therefore, in order to remove and replace a unit, the user must have access to the space beneath plate 32 in order to engage the nut used to fasten the unit, and specifically the bolt, on the plate. In fact, while attempting to gain access to the portion of the fastener between the plate and the tool or other surface on which the plate is mounted, the user is actually prone to damaging other gas handling devices mounted adjacent the device being repaired.
This problem is magnified when the gas handling device is used to deliver a toxic, pyrophoric or other dangerous gas to the tool. Because of the likelihood of injury to users if the gas leaks from the device, the gas handling device is housed in a box that is vented to an external source. The box protects users from being exposed to a harmful gas, but causes the user's working area to be constrained on virtually all sides of the device. As such, it is extremely difficult to access and manipulate nuts or other components which are mounted beneath plate 32.
A further disadvantage of the gas handling device shown in FIG. 1 is that the plate must be mounted in a fixed position on or adjacent to the tool to which it provides a flow of gas. Plate 32 is mounted by drilling holes in selected mounting positions to receive a bolt and nut or other suitable fastening device to secure the device in a fixed operative position. Because it is not known in advance where the exact positioning of the holes must be, the holes must be drilled within the clean room in which the tool is used, thereby creating the risk of particulates and other contaminants being introduced into the gas handling units and the tool, as discussed above.
Yet another disadvantage with the gas handling device shown in FIG. 1 is that it must be assembled and installed on site. Specifically, the dimensions of the device and the span or length available on the device's base plate or other mounting unit are not known to the installer until the installer is present at the tool with which the device is to be used. This is often due to the continually changing or custom configurations of the gas handling units, which are typically available from a variety of suppliers. Therefore, the device must often be assembled manually at the site. This not only increases the time, and hence expense, necessary to install the device, but also significantly increases the risk that particulate or other contaminants will be introduced into the gas handling units. It should be understood that particulate on the micron level in size are sufficient to clog or otherwise cause gas handling units to malfunction or contribute to manufacturing or yield problems.
A related disadvantage of assembling and installing the devices on site is that the installer of piping to the tool does not know the dimensions or space needed for the gas handling device. Accordingly, the person installing the piping is able to route or install piping adjacent the tool, but then must wait until the device is installed before completing the installation. This commonly results in the installer making additional trips to the site, thereby further increasing the cost of installation and the time necessary to get the tool up and running.
With the above problems in mind, it is a general object of the present invention to provide a gas handling device in which the gas handling units mounted thereon are slidably and adjustably mounted with respect to the device and selectively securable thereon.
Another object is to provide such a device with dual laterally spaced and longitudinally extending tracks, each configured to engage a portion of a gas handling unit to retain and stabilize the unit on the device.
Yet another object is to provide a gas handling device which is of a standard length and which may be mass-produced with a plurality of gas handling units mounted thereon.
Still another object is to provide a gas handling device which enables gas handling units to be mounted thereon, adjusted and removed therefrom without requiring the user to access the region beneath the device.
Another object is to provide a gas handling device which may be adjustably mounted for operative use on or adjacent to a tool used in the semiconductor manufacturing process without requiring alteration of the surface on which the tool is mounted.
Yet another object is to provide a method for mounting a plurality of gas handling units on a gas handling device without requiring alteration of the gas handling device.
Still another object is to provide a method for mounting a gas handling device for operative use on or adjacent to a tool used in the semiconductor manufacturing process without requiring alteration of the surface on which the device is mounted.
A further object is to provide a gas handling device that stabilizes the fittings and mechanical joints of the gas handling device without requiring additional field work.